What Documentation Does the IRS Require for Specific Identification?
Anyone selling only part of a crypto holding eventually runs into a choice about accounting method. The default approach picks which units are considered sold on its own, but a taxpayer can instead specifically identify which coins left the wallet, provided the records support it.
The short answer
Using specific identification for a crypto sale generally requires records that identify the exact units sold, the wallet or account they came from, the date and time they were originally acquired, and the price paid for them, all documented at or near the time of the transaction rather than reconstructed later. Without that level of detail, the sale is typically treated under a standard default ordering method instead.
How specific identification differs from the default method
Most people who never make an active choice end up using a first-in-first-out approach, where the oldest units in a holding are treated as the ones sold first. That default has the advantage of requiring almost no extra recordkeeping, but it also removes any control over which lot, and therefore which cost basis, gets matched to a given sale. Specific identification flips that: instead of a mechanical rule choosing the units, the taxpayer designates them, which means the documentation has to do the work the default method would otherwise handle automatically. For a fuller comparison of how the default method behaves in practice, see how FIFO accounting works for selling cryptocurrency.
The pieces of information that generally need to line up
- Acquisition date and time. The record needs to show when the specific unit being sold was originally received, not just an approximate purchase window.
- Original cost basis. The exact price paid for that unit, including any fees that were part of the purchase, needs to be documented and traceable back to the acquisition.
- Unit-level identification. The record should identify which specific unit, wallet, or sub-account the coins being sold came from, distinguishing them from other units of the same asset acquired at different times.
- Confirmation at the time of sale. The identification generally needs to happen when the transaction occurs, or be captured in records maintained close to that point, rather than assigned after the fact once it’s clear which choice produces a better outcome.
Why the timing of the paperwork matters
The requirement that identification happen close to the time of sale exists largely to prevent selective hindsight, where someone waits to see how prices moved and then labels a sale using whichever lot produces the most favorable result. Because of that, contemporaneous records carry far more weight than a reconstruction built weeks or months later from memory or partial statements.
Why this is harder with crypto than with a typical brokerage account
A share of stock held at a single brokerage usually comes with an account statement that already tracks lots automatically. Crypto often doesn’t work that way, since the same holder may have coins spread across an exchange account, a hardware wallet, and a handful of other addresses, each with its own partial transaction history. That fragmentation is a large part of why tracking cost basis for crypto is difficult compared with more traditional investments, and it’s also why documentation gaps tend to show up exactly where specific identification would otherwise be most useful, such as when trying to tax-loss harvest a particular position.
The takeaway
Specific identification can be a legitimate way to match a sale to a particular lot, but it depends entirely on records that exist before the question ever comes up, not ones built to fit a preferred answer afterward. Because documentation standards and reporting requirements around digital assets continue to change, and because a single missing detail can undermine an otherwise reasonable position, this is an area worth reviewing with a tax professional who can look at the actual records on hand.